Telephone-exchange system.



L. H- JOHNSON.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED APR. 7. 19:5.

Patented Apr. 3, 1917.

fo opers telephone W17 Mven/ow:

Lew/Is h. Johnson Tl TT T TE T LEWIS I-I. JOHNSON, OF BLOOMFIELD, NEW JERSEY, ASSIGNOR, BY lVlIESNE ASSIGN- MENTS, T0 WESTERN ELECTRIC COMZPANY, INCORPORATED, A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed April 7, 1915.

To all whom it may concern:

Be it known that 1, LEWIS H. J OHNSON, a citizen of the United States, residing at Bloomfield, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and eXact description.

This invention relates to telephone eX- change systems, and more particularly to such systems of the central'energy type, the object of this invention being to provide improved. signaling means for such systems.

In accordance with this invention means are associated with the connecting circuit whereby, when the connecting circuit is con nected to a calling subscribers line and the calling subscribers receiver has been re stored to the switchhook and subsequently removed therefrom, the usual line signal associated with the line is caused to operate intermittently to furnish a recall signal.

This invention is illustrated in the accompanying drawing in which all apparatus is shown in its normal and unactuated condition.

There is shown in the drawing a telephone exchange system containing one embodiment of this invention, and comprising the usual subscribers stations, A and B, and a cord circuit C located at a central office for interconnecting the subscribers stations. It is believed that this invention will be fully understood from description of the operation of the system shown in the drawing, and it will be so described.

Subscriber A wishing to converse with subscriber B, signals the operator in the usual manner. The operator, answering, inserts the answering plug in a jack of the calling line, causing the operation of supervisory relay 13 included in bridge of the talking strands of the cord circuit. Relay 13, in operating, short circuits winding 68 of marginal relay 18, whereupon relay 18 and marginal cutoff relay 19 are actuated. The energizing circuittor these relays may be traced from battery 15, contact 16 of relay 13, winding 17 of relay 18, and winding of cut-off relay 19 to ground. Relay 18 in operating completes a locking circuit for itself from battery 10 through contact 21. it is to be noted at this point that marginal relay 18 will not attract its armatures when both wind g are in lud d in the cir Specification of Letters Patent.

Patented Apr. 3, 1917.

Serial No. 19,791.

but will maintain its armatures in attracted position when current traverses both windings, also that cutofi' relay 19 will not operate when in series with both windings of relay 18, but will operate when in series with winding 17 only. Relay 18 in operat- 111g, which operates and connects the operators telephone set across the talking strands of the cord circuit in the usual manner. The operator, finding that subscriber B is wanted, inserts the calling plug in a jack of subscriber Bs line, causing the operation of relays 27 and 30 and supervisory signal 53. Relay 27, in operating causes the dis connection of the operators telephone set from the talking strands, and causes the automatic application of a source of ringing current 11 to the called line in a manner well understood, for operating the call signal bell 4E3. Subscriber B, in responding, removes the receiver from the switchhook, thereby causing the disconnection of the ringing current from the line in a manner well understood, after which calling superalso completes a circuit for relay 28 visory relay 52 in bridge of the talking strands of the cord circuit operates, efiacing supervisory signal 53.

Upon finishing the conversation, subscribers A and B restore their respective receivers to the switchhooks, whereupon relays 13 and 52 release, permitting supervisory signals 53 and 55 to operate to give disconnect signals. If the operator is not busy, the answering and calling plugs are -removed from the jacks and all apparatus returned to normal. However, it as is frequently the case during busy periods, the operator does not immediately take down the connection, and if subscriber A desires to immediately attract the attention of the operator to make another call, or for any other purpose the subscriber must, in systems heretofore used, move the switchhook up and down repeatedly to cause the flash ing of the supervisory signal. The position of the supervisory signal on the switchboard is such that the flashing thereof does not readily attract the attention of the operator, and unless the switchhook is moved rather slowly the supervisory relay does not follow the switchhook which results in rendering the flashing of the supervisory signal rather uncertain. The present invention provides for the automatic flashing ot the usual line lamp when the calling subscriber has restored the receiver to the switchhook and has subsequently removed it therefrom. The manner in which the line signal of the calling subscriber is caused to flash will now be described. When the receiver of subscriber A is restored to the switchhook, the deenergization of supervisory relay 13 causesthe operationof relay 62 over a circuit from battery 15, through contact 57 of relay 13, contact 60 of relay 61, winding of relay 62, contact 29 of relay 18 to ground. Relay 62, in operating, closes its contact 63, thereby.completing a path from battery 64 through the winding of relay 12, contact I 63 of relay 62, windings of relays 61 and 62 and contact 29 of relay 18 to ground. Re-

lays 12 and .61, due to the short circuit from battery 15, are not operated at this time.

The subsequent removal of the receiver from the switchhook at substation A causes the operation of relay 13 which opens the short circuit of relays 12 and 61, which now operate. Relay 12 in operating removes battery supply from the windings of relay 13 which in releasing causes the operation of supervisory signal 55, and opens the looking circuit from battery 10, through the winding 17 of relay 18, and opens the short circuit of winding 68 of marginal relay 18, while the operation of relay 61 connects interrupter 67 in shunt of winding 68 of marginal relay 18. As before explained, cutoff relay 19 is marginal and will not remain actuated when in series with windings 17 and 68 of relay 18, but will be operated when in series with only winding 17 of this relay. The rotation of interrupter 67 intermittently short-circuits winding 68 of relay 18, whereby cutoff relay 19 is alternately energized and deenergized. The alternate energization and deenergization of cutoff relay 19 alternately connects and disconnectsline relay 5 from the line wires of substation A, 'whereupon the circuit ofline signal 7 is intermittently closed. The operator observing that line signal 7 is flash ing removes the plugs from the jacks restoring all cord circuit apparatus to normal position and reinserts the answering plug ,7 in the jack of the calling line whereupon the operators telephone set is associated with the talking strands of the cord circuit and the operator may communicate with the subscriber. While for convenience and simplicity, the line signal is shown in only one position, it is to be understoodthat the line signals are multiplied through the various positions, so that any idle operator may note the flashing of this signal and insert an answering plug in a jack of the calling line and ascertain the wants of the calling subscriber.

In telephone exchange systems of the common battery typeheretofore used it has been necessary, when desiring to attract the attention of the operator, to repeatedly operate the switchhook to cause thereby the operation of the supervisory signal. This manner of attracting the operators attention has always been very unsatisfactory, due in part to the inability to cause the operation of the supervisory signal upon each movement of the switchhook. It is also diliicult for an operator, when busy, to direct attention to the supervisory signals because the operator is primarily concerned with the answering of calls and completing connections. It is usual therefore for the operators attention to be directed principally to the line signals. By employing a telephone system embodying the present invention, the unsatisfactory conditions prevailing in existing telephone systems are overcome and a means is provided whereby the subscriber may attract the attention of an operator in the least possible time.

Since the apparatus for controlling the flashingof the line signal is associated with the answering end of the cord circuit, it is obvious that the calling subscriber may, at any time after the answering plug has been inserted in the jack, cause the automatic flashing of the associated line signal. While in this description several batteries have been referred to, it is obvious that one battery may be substituted therefor, and such is the usual practice.

What is claimed is:

1. In a telephone exchange system, a subscribers line terminating at a central ofiice, a link circuit thereat connected to said line, a line signaling device and a cut-off relay controlling said device associated with said line, a supervisory relay controlled over said line from the subscribers station, a second relay, an energizing circuit therefor completed upon the deenergization of said supervisory relay in response to the restoration of the receiver to the switchhook, a locking circuit for said second relay completed upon the energization thereof and independent of said supervisory relay, a source of interrupted current, and a third relay conditioned for operation upon the energization of said second relay and operated upon the subsequent energization of said supervisory relay due to removal of receiver from switchhook to connect said source of interrupter current in circuitwith said cut-off relay, whereby said line signaling device is caused to operate intermittently to furnish a distinctive signal.

2. In a telephone exchange system, a calling subscribers line terminating at a central ofiice, a line signaling device and a cut-off relay controlling said device associated with said line, a link circuit connected to said line, a supervisory relay energized upon connection of said link with said line and controlled from the subscribers station, a

sleeve relay associated with said link and energized upon the energization of said supervisory relay, a second relay conditioned for operation upon energization of said sleeve relay and operated upon the deenergization of said supervisory relay due to the restoration of receiver to switchhook, a locking circuit for said second relay established upon the energization thereof to place said second relay without the control of said supervisory relay, a source of interrupted current, a third relay conditioned for operation upon the energization of said second relay and operated upon a subsequent energization of said supervisory relay due to removal of receiver from switchhook for connecting said source of interrupted current in circuit with said cut-oft relay, whereby said line signaling device is caused to operate intermittently to furnish a distinctive signal.

3. I11 a telephone exchange system, a subscribers line terminating at a central otlice, a link circuit thereat connected with the line, a line signaling device and a cut-oil relay controlling the signaling device asso ciated with the line, a source of interrupted current, and means controlled from the connected substation for including said source of interrupted current in circuit with the cut-off relay to cause the intermittent operation of the line signaling device.

4. In a telephone exchange system, a subscribers line terminating at a central office, a link circuit thereat connected with the line, a line signaling device and a cut-off relay controlling the signaling device asso ciated with the line, a source of interrupted current, and a plurality of relays associated with the link circuit and controlled from the connected substation for including said source of interrupted current in circuit with the cut-off relay to cause the intermittent operation of the line signaling device.

5. In a telephone exchange system, a subscribers line terminating at a central office,

a link circuit thereat connected with the line, a line signaling device and a cut-off relay controlling the signaling device associated with the line, a source of interrupted current, and a relay associated with the link circuit conditioned for operation upon the restoration to the switchhook of the receiver at the connected substation, and operated upon the subsequent removal thereof for including said source of interrupted current in circuit with the cut-oii' relay to cause the intermittent operation of the line signaling device.

6. In a telephone exchange system, subscribers lines terminating at a central oflice, a signaling device for each line, a link circuit connected to one of said lines, a source or interrupted current, and a plurality of relays associated with the link circuit and operated upon the restoration to and the subsequent removal from the switchhook of the receiver at the connected substation to associate said source of interrupted current with the line signaling device of the connected line, thereby causing said device to operate intermittently.

7. In a telephone exchange system, a subscribers line terminating at a central oflice, a link circuit thereat connected with the line, a line signaling device individual to said line, a source of interrupted current, and a relay associated with the link circuit and conditioned for operation upon the restoration of the receiver to the switchhook at the connected substation and operated upon the subsequent removal thereof while the link circuit is connected with the line for associating the source of interrupted current with the signaling device to cause the inter mittent operation thereof.

In witness whereof, I hereunto subscribe my name this 6th day of April A. D., 1915.

LEWIS H. JOHNSON.

Witnesses:

E. EDLER, K. L. STAHL.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patent Washington, I). C. 

